The use of waterproof membranes for covering a roof such as a flat roof and the use of mechanisms for securing the edges of such waterproof membranes at the roof edges is well known. In the construction of such mechanisms, or roof edge fascia systems as they are commonly referred to, a dam means is secured to the edge of a roof. The dam means often includes a horizontal portion adapted to be secured to the roof, an upwardly inclined portion or cant extending from the horizontal portion and having an upper edge, and a vertical portion extending downwardly from the upper edge of the cant. A waterproof membrane is laid across the surface of the roof such that an edge of the membrane is laid up against the cant portion of the dam means, over the upper edge and down against the outside surface of the vertical dam portion. A snap-on cap is also included which overlays and clampingly engages the dam means and the interposed membrane. Such membranes are then covered with a suitable layer of ballast such as gravel. The weight of the layer of ballast on the membrane is intended to hold the membrane down against the roof surface. The dam means serves to retain the gravel ballast and control water drainage from the roof. An example of such a system is described and illustrated in the Butzen U.S. Pat. No. 4,419,850.
Although such systems are satisfactory in performance, the utilization of such a dam means and snap-on cap does not readily lend itself to the use of cast roof paver blocks as ballast or other sheetlike insulation to overlay the membrane. Such paver blocks generally comprise cast square concrete blocks, approximately 11/2 to 2 inches thick and 2 feet on edge, and are placed on the membrane in edge-to-edge relation. Although the insulation sheets are of similar thickness, approximately 2 to 3 inches thick, they are substantially longer and wider than the dimensions of the paver blocks, may be comprised of a variety of materials and are interlockably engagable by ridges and grooves located in their sides and ends. The above-described system, when utilizing paver blocks or insulation sheets, does nothing to prevent winds of sufficient velocity at the roof top or at the edge of the roof from shifting the paver blocks or insulation sheets or from totally lifting them upwardly and away from the membrane. Such movement by the paver blocks can quite obviously damage the membrane or, in the case of either paver blocks or insulation sheets, result in damage to the blocks or sheets themselves.